Sending Notifications in Pipeline

Rather than sitting and watching Jenkins for the job status, I want Jenkins to send notifications when events occur. There are Jenkins plugins for Slack, HipChat, and even email among others.

Note: Something Is Happening!

I think we can all agree that getting notified when events occur is preferable to having to constantly monitor them just in case. I'm going to continue from where I left off in my previous post with the Hermann project. I added a Jenkins Pipeline with an HTML publisher for code coverage. This week, I'd like to make Jenkins notify me when builds start and when they succeed or fail.

Setup and Configuration

First, I select targets for my notifications. For this blog post, I'll use sample targets that I control. I've created Slack and HipChat organizations called bitwiseman, each with one member: me. For email, I'm running a Ruby SMTP server called Mailcatcher that is perfect for local testing such as this. Aside from these concessions, the configuration will be much the same in a non-demo situation.

Next, I install and add server-wide configuration for the Slack, HipChat, and email-ext plugins. Slack and HipChat use API tokens. Both products have integration points on their side that generate tokens that I copy into my Jenkins configuration. Mailcatcher SMTP runs locally. I just point Jenkins at it.

Here's what the Jenkins configuration section for each of these looks like:

Original Pipeline

Now I can start adding notification steps. Just like in the previous post, I'll use the Jenkins Pipeline Snippet Generator to explore the step syntax for the notification plugins.

Here's the base pipeline before I start making changes:

 stage 'Build' 

 node {
   // Checkout 
   checkout scm 
   
   // install required bundles 
   sh 'bundle install' 
   
   // build and run tests with coverage 
   sh 'bundle exec rake build spec'
   
   // Archive the built artifacts 
   archive (includes: 'pkg/*.gem') 
   
   // publish html 
   // snippet generator doesn't include "target:" 
   // https://issues.jenkins-ci.org/browse/JENKINS-29711. 
   publishHTML (target: [ 
       allowMissing: false, 
       alwaysLinkToLastBuild: false, 
       keepAll: true, 
       reportDir: 'coverage', 
       reportFiles: 'index.html', 
       reportName: "RCov Report" 
      ]) 
 } 

Note: This pipeline expects to be run from a Jenkinsfile in SCM. To copy and paste it directly into a Jenkins Pipeline job, replace the checkout scm step with git 'https://github.com/reiseburo/hermann.git'.

Job Started Notification

For the first change, I decide to add a "Job Started" notification. The snippet generator and reformatting make this straightforward:

 node {
   
   notifyStarted()
   
   /* ... existing build steps ... */ 
 }

 def notifyStarted() {
   // send to Slack 
   slackSend (color: '#FFFF00', message: "STARTED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]' (${env.BUILD_URL})") 
   // send to HipChat 
   hipchatSend (color: 'YELLOW', notify: true, 
       message: "STARTED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]' (${env.BUILD_URL})" 
     ) 
   
   // send to email
   emailext ( 
       subject: "STARTED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]'", 
       body: """<p>STARTED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]':</p>
         <p>Check console output at "<a href="${env.BUILD_URL}">${env.JOB_NAME} [${env.BUILD_NUMBER}]</a>"</p>""",
       recipientProviders: [[$class: 'DevelopersRecipientProvider']]
     )
 }

Since Pipeline is a Groovy-based DSL, I can use string interpolation and variables to add the exact details that I want in my notification messages. When I run this, I get the following notifications:

Job Successful Notification

The next logical choice is to get notifications when a job succeeds. I'll copy and paste based on the notifyStarted method for now and do some refactoring later.

 node {
 
   notifyStarted()
 
   /* ... existing build steps ... */
 
   notifySuccessful()
 }
 
 def notifyStarted() { /* .. */ }
 
 def notifySuccessful() {
   slackSend (color: '#00FF00', message: "SUCCESSFUL: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]' (${env.BUILD_URL})")
 
   hipchatSend (color: 'GREEN', notify: true,
       message: "SUCCESSFUL: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]' (${env.BUILD_URL})"
     )
 
   emailext (
       subject: "SUCCESSFUL: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]'",
       body: """<p>SUCCESSFUL: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]':</p>
         <p>Check console output at "<a href="${env.BUILD_URL}">${env.JOB_NAME} [${env.BUILD_NUMBER}]</a>"</p>""",
       recipientProviders: [[$class: 'DevelopersRecipientProvider']]
     )
 }

Again, I get notifications, as expected. This build is so fast that some of them are even on the screen at the same time:

Job Failed Notification

Next, I want to add a failure notification. Here's where we really start to see the power and expressiveness of Jenkins Pipeline. A Pipeline is a Groovy script, so as we'd expect in any Groovy script, we can handle errors using try-catch blocks.

 node {
   try {
     notifyStarted()
 
     /* ... existing build steps ... */
 
     notifySuccessful()
   } catch (e) {
     currentBuild.result = "FAILED"
     notifyFailed()
     throw e
   }
 }
 
 def notifyStarted() { /* .. */ }
 
 def notifySuccessful() { /* .. */ }
 
 def notifyFailed() {
   slackSend (color: '#FF0000', message: "FAILED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]' (${env.BUILD_URL})")
 
   hipchatSend (color: 'RED', notify: true,
       message: "FAILED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]' (${env.BUILD_URL})"
     )
 
   emailext (
       subject: "FAILED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]'",
       body: """<p>FAILED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]':</p>
         <p>Check console output at "<a href="${env.BUILD_URL}">${env.JOB_NAME} [${env.BUILD_NUMBER}]</a>"</p>""",
       recipientProviders: [[$class: 'DevelopersRecipientProvider']]
     )
 }

Code Cleanup

Lastly, now that I have it all working, I'll do some refactoring. I'll unify all the notifications in one method and move the final success/failure notification into a finally block.

 stage 'Build'
 
 node {
   try {
     notifyBuild('STARTED')
 
     /* ... existing build steps ... */
 
   } catch (e) {
     // If there was an exception thrown, the build failed
     currentBuild.result = "FAILED"
     throw e
   } finally {
     // Success or failure, always send notifications
     notifyBuild(currentBuild.result)
   }
 }
 
 def notifyBuild(String buildStatus = 'STARTED') {
   // build status of null means successful
   buildStatus =  buildStatus ?: 'SUCCESSFUL'
 
   // Default values
   def colorName = 'RED'
   def colorCode = '#FF0000'
   def subject = "${buildStatus}: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]'"
   def summary = "${subject} (${env.BUILD_URL})"
   def details = """<p>STARTED: Job '${env.JOB_NAME} [${env.BUILD_NUMBER}]':</p>
     <p>Check console output at "<a href="${env.BUILD_URL}">${env.JOB_NAME} [${env.BUILD_NUMBER}]</a>"</p>"""
 
   // Override default values based on build status
   if (buildStatus == 'STARTED') {
     color = 'YELLOW'
     colorCode = '#FFFF00'
   } else if (buildStatus == 'SUCCESSFUL') {
     color = 'GREEN'
     colorCode = '#00FF00'
   } else {
     color = 'RED'
     colorCode = '#FF0000'
   }
 
   // Send notifications
   slackSend (color: colorCode, message: summary)
 
   hipchatSend (color: color, notify: true, message: summary)
 
   emailext (
       subject: subject,
       body: details,
       recipientProviders: [[$class: 'DevelopersRecipientProvider']]
     )
 }

You Have Been Notified!

I now get notified twice per build on three different channels. I'm not sure that I need to get notified this much for such a short build. However, for a longer or complex CD pipeline, I might want exactly that. If needed, I could even improve this to handle other status strings and call it as needed throughout my pipeline.